Why are they necessary?
Where are they used?
Why are we concerned with PFAS, instead of other common contaminants like lead?
Polyfluoroalkyl substances (PFAS) are a large family of man-made
chemicals. They share in common the fact that all chemical compounds in
this family incorporate several atoms of the element fluorine. PFAS are
sometimes called PFCs (per- or poly-fluorinated compounds). You might also
see specific compounds referred to (e.g., PFOA, PFOS). Two of the chemical
compounds in the PFAS family that were the most commonly used and produced
are PFOA
(also referred to as C8)
and PFOS.

Here, we'll use the term PFAS (plural, PFAS) to refer to the larger group
of chemicals, unless we are specifically referring to PFOA or PFOS.

PFAS are (or have been) used to make consumer goods resistant to water,
grease, or stains, in products like Gore-Tex rain gear, Teflon no-stick
cookware, and Scotchguard stain-repellent for carpets or furniture
fabric. PFAS are also found in foams used by firefighters to extinguish
oil and gas fires.
→ REFERENCE
BU SPH, PFAS Factsheet
→ REFERENCE
The New Lead - Perfluorinated Compounds (PFCs)
PFAS are only one class of many "emerging contaminants" being studied by
public health scientists. They are called "emerging contaminants" because
they have largely gone unregulated over years of use, and now a growing
body of science indicates that these chemicals are toxic. The emerging
contaminants include many very common chemicals in widespread, high-volume use
resulting in regular exposure to the general population.

The toxic effects of these chemicals vary. However, many emerging
contaminants have been found to have subtle but important health effects,
like disruption of normal hormone function. In most cases, the developing
fetus and children are most susceptible to these "endocrine disruption"
effects. In addition, some emerging contaminants have important effects on
the developing brains of the fetus and of children.
→ REFERENCE
Kristof, 'How Chemicals Affect Us'

Finally, many emerging contaminants—including the PFAS chemicals—are
important because they are very persistent in the environment, meaning
that they will be present in the air, water, soil, and in humans and
animals for many years and decades after we stop producing them.
→ REFERENCE
EWG, Dirty Dozen Endocrine Disruptors

PFAS have a unique chemistry, related to their unusual ability to
function as water barriers and non-stick surfaces. In particular, and
unlike many other important toxics, PFAS are water soluble (that is, they
can dissolve in water). Therefore, they are commonly found as contaminants
in water, including drinking water, and they can be more easily carried
into the body and bloodstream than many other toxic chemicals.

PFAS are still a relatively new class of chemical compounds, and we have
much more to learn about their health effects. Testing for PFAS can be
difficult and expensive, and interpreting the results is challenging. In
fact, it is very likely that public health scientists have not yet
identified all the PFAS chemicals that are in use—so the story of PFAS
contamination is still in its beginning stages.

See also:How can I tell whether my water has been contaminted?—see #WATERHow can I tell whether there are PFAS in my body?—see #BLOOD
PFAS are now found almost everywhere in our environment, and it is
difficult to quantify how much people are exposed to and exactly how they
are exposured. For most people in the USA, who are exposed at so-called
"background," or "average", levels of contamination, the primary source of
exposure is most likely from consuming foods that were wrapped in
PFAS-coated packaging. However, people with higher than average exposure
are most likely drinking water that has been contaminated with PFAS.

WATER

Because PFAS are water soluble, the biggest threat of high exposure is through
drinking water. Until recently, we thought that only a few water supplies were
vulnerable to contamination from large PFAS emissions—for example, the water
systems in Ohio and West Virginia that were contaminated by DuPont's
Parkersburg, WV facility.
→ REFERENCETHE TEFLON TOXIN: DuPont and the Chemistry of Deception

However, we now know that PFAS contamination is much more common. PFAS have
been found in public drinking water supplies serving an estimate 6 million US
residents in excess of federally recommended levels for protecting public
health In a survey of public drinking water systems nationwide, PFAS were
measured in 33 states at the minimum reporting levels required by the US EPA
(the government agency with authority to enforce the Safe Drinking Water
Act). PFAS have now been found in some of the drinking water supplies
in all six New England states.
→ REFERENCE
'Unsafe levels of toxic chemicals found in drinking water for six million Americans'
→ REFERENCE
Hu X, et al. (2016) Environ. Sci. Technol. Lett. 3, 344-350
In Bennington, VT, where drinking water contamination led some residents to have had
their blood tested for PFAS, the average PFOA levels were nearly five times the
national average, with some residents showing levels more than 100 times higher --
far in excess of what the EPA considers safe.
→ REFERENCE
Bennington blood tests show high PFOA

Contaminated water is most likely to be found near manufacturing facilities
that used PFAS, or in areas where PFAS were used in firefighting foams,
especially on military bases. The use of firefighting foams in training
location results in a large amount of PFAS on the ground, where it can leech
into groundwater sources (wells) or run off into surface water sources
(streams, rivers, reservoirs).

PFAS IN THE ENVIRONMENT AND THE BODY

Because of PFAS are persistent in the environment, remaining for years or decades
without breaking down, they are capable of traveling long distances, especially in
water, and may be found far from the locations where they were initially released
into the environment.

The specific chemical properties of PFAS cause them to stay in the human body
for a long time—many years. This "bioaccumulation" means that even relatively
low exposures to PFAS can, over time, lead to very high levels in the blood
and tissues. (The same is true with many other chemical compounds, like PCBs,
flame retardants, or most famously, DDT.) In addition, people people who are
exposed to PFAS are often exposed to a mix of PFAS chemicals. Once in the
body, they may be transformed into more or less toxic forms of
PFAS. Scientists are also finding that some related chemicals can become PFAS
when they enter the body.

In addition to deliberate and accidental pollution from industry, and runoff
from firefighting foams, PFAS may enter the environment in many other
ways. For example, washing a rain jacket that is coated with PFAS-based water
repellents will remove some of this coating, and send the PFAS into the
wastewater stream. Although the amount released this way seems small, the
widespread use, high persistence, and bioaccumulating properties of PFAS
chemicals means that these small amounts can add up and last for a very long
time. Once in the environment, they might have effects on plants and
animals. They can also then enter the food chain and lead to later human
exposure.

FOOD

PFAS (and related chemicals) are found in many food packaging materials,
including microwave popcorn bags and pizza boxes. As with other toxic
chemicals, there is usually no requirement for labeling PFAS-containing
products, so it is difficult for the consumer to avoid them.

Eating fish caught in contaminated waters may be another significant route of
PFAS exposure.

Because PFAS contamination in the environment is so widespread, it is also
likely to be found at low levels in meat and dairy products, even far from
contamination sources.

WORKER EXPOSURE

Finally, workers in facilities using PFOA and PFOS may be (or may have been)
highly exposed to PFOA, PFOS, and related chemicals. This exposure might come
from inhaling PFAS chemicals directly, or absorbing them through the skin, or
even ingesting them (for example, when eating with PFAS-contaminated hands).

SUMMARY

Given their widespread use over many decades, it is no surprise that today
nearly all people living in the US who are tested have at least low levels
of PFAS in their blood, and some have much higher levels.
→ REFERENCE
'Unsafe levels of toxic chemicals found in drinking water for six million Americans'

Because of the persistence and bioaccumulation of PFAS, even people who
don't use PFAS chemicals, and who live far from contaminated sites, can
still be exposed through diet and water. Although the average exposures
experienced by the general population are sometimes referred to as
"background" levels, there is nothing natural or even safe about them,
since PFAS were not present before humans started manufacturing them.

In communities with contaminated water supplies, however, PFAS levels are
far higher than "background". That exposure is seen by many as an
involuntary intrusion into their bodies. This is referred to
as "toxic trespass"—the idea that a polluter is trespassing on your body by
introducing toxic chemicals without your consent, and which you don't know
about, didn't agree to, and may not even use.
→ REFERENCE
Sandra Steingraber's War on Toxic Trespassers

Now that we know that many people are exposed, our next task is to figure
out what health effects that exposure might cause. For that topic, see #effects.

Is PFC contamination ongoing, or has it been stopped?
What are the implications of PFAS contamination for new water sources?

Because PFAS are water soluble, the biggest threat of high exposure is through
drinking water. Until recently, we thought that only a few water supplies were
vulnerable to contamination from large PFAS emissions — for example, the water
systems in Ohio and West Virginia that were contaminated on a very large scale by DuPont's
Parkersburg, WV facility.

Today, we're finding that many sources can contribute to PFAS in lakes, rivers, or
underground aquifers. In some areas, the largest source is when firefighting
chemicals, which often contain PFAS, are allowed to run off onto the ground or into
a stream. This may not sound like a major source, but firefighter training can use
huge volumes of these substances over and over at the same spot — a training
facility or an airport, for example. These PFAS-containing foams can then leach
into water supplies, contaminating them.

Since PFAS are used for many purposes, there are other, usually smaller, sources.
For example, clothes treated with PFAS will leech more PFAS out into the sewer --
and possibly into the groundwater — with every laundry cycle. (Breathable
water-proof or water-resistant fabrics are most often treated with PFAS.)

PFAS chemicals are very persistent in the environment, and won't easily break down.
This means that once contamination has occurred, the water supply will likely be
contaminated for many years to come.

PFOA and PFOS, historically the two most important PFAS chemicals, are no longer made in
the USA. However, there are a great many related compounds with similar properties,
which may be use Furthermore, stocks of PFAS firefighting foams can be stored for
decades, and are likely to be used in firefighting training long into the future,
providing future sources of contamination.

How strong is the scientific link between exposure to PFAS and health outcomes?
Where do PFOAs accumulate in the body?
Why do PFAS show up in some people more than others?
We know that most people living in the US are exposed to at least some
level of PFAS chemicals—and many of us are highly exposed. (See #exposed.)
But what are the effects of those chemicals on people?

As is the case with many other "emerging contaminants," PFAS have been in
use for a long time—many decades, in the case of PFOA and PFOS—but we
are only now learning about their health effects. This problem of "using
before understanding" occurs regularly because the US does not require
testing of most new chemicals before they are used commercially. (For more
on the problem of regulating emerging contaminants, see #future.)

The federal Agency For Toxic Substances and Disease
Registry lists these health effects as potentially being associated with
PFAS exposure in humans:
→ REFERENCE
Agency For Toxic Substances and Disease Registry, Health Effects of PFAS

Not all of these effects will necessarily lead to
disease; changes in liver enzymes may never lead to a liver disease, for
example. So there is still uncertainty regarding the significance of some of these
changes. However, other effects (e.g., cancers) represent clearer risks.
It's also important to note that not everyone is equally susceptible to these
effects. For example, developing fetuses and children are much more susceptible
to the endocrine disrupting effects on the thyroid, the
brain, and the immune system, since those hormonal systems are still being
formed and are especially sensitive during development.

DATA FROM HUMAN STUDIES

Our strongest evidence for the effects of chemicals is from studying
people who are exposed. The study of causes of illness in humans is
called epidemiology.

Of course, we can't test dangerous chemicals directly on people. Instead, we
look for people and communities who are already exposed—what scientists
sometimes call "natural experiments"—and compare them with those who are not
exposed to see if we can find differences in their health outcomes. We search
for a difference in the health of these populations that can only be explained
by the exposure of interest (in this case, PFAS). Unfortunately, epidemiology is
extremely difficult and expensive, often requiring a great deal of information
about thousands of people over many years to see strong patterns of disease and
be able to attribute the disease to the exposure. More importantly, because each
of us is so different, because we are each exposed to so many different
chemicals, many of which can cause the same or similar diseases, it is nearly
impossible to separate out the effects of just one chemical or class of
chemicals.

This means that epidemiology is usually not a very sensitive tool for
investigating health effects of low-level exposures. In fact, one
prominent epidemiologist has defined a disaster as "an event so severe
that even an epidemiologist can detect it."
→ REFERENCE
Ozonoff, quoted in Wartenberg, Exposure Science: A Tool for Assessing Public Health Impact

Several large groups of people exposed to PFAS—"cohorts"—have now
been studied. The largest cohort, centered around the Ohio River near
Parkersburg, WV, was exposed to PFOA in their drinking water over several
decades, as the DuPont facility there emitted that chemicals into the air
and water. The study, led by the C8 Science Panel
→ REFERENCE
C8 Science Panel website
, was undertaken after a
lawsuit against DuPont, and led by by three neutral epidemiologists
appointed by the court. ("C8" is another term for PFOA.)
(As an example of the difficulty and
expense of large-scale epidemiology, the C8 study took seven years and
cost $35 million dollars.)

At the conclusion of the study, the C8 Science Panel reported to the judge
that they had found
"probable links" between PFAS exposure and cancer, thyroid disease, high cholesterol, ulcerative colitis, and pregnancy-induced hypertension.
→ REFERENCE
C8 Science Panel: Probable Link Reports
Although these "probable links" represent a legal conclusion rather than a
traditional scientific one, they summarize most of the best data available
to epidemiologists by 2013.
The Science Panel did not find a "probable link"
for many other outcomes, e.g., neurodevelopmental disorders in
children, birth defects, low birth weight.
Other epidemiologic studies have broadly confirmed the findings of the C8
Science Panel. However, it won't be surprising if future studies are able to
identify health effects that the C8 Science Panel was not. Very rarely in the
history of science has a single study set the standard for what is considered
general knowledge.
DATA FROM ANIMALS

Since human data on the effects of PFAS is so limited, and so difficult to
collect, we also study the effects of these chemicals on animals.

In animal studies, PFAS have been shown to have adverse effects on multiple
organs, to cause developmental problems to offspring, to reduce immune function,
and to disrupt normal endocrine activity.

Once PFAS are in the body, they
will remain until they are excreted in urine or feces
over a period of many years.

ENDOCRINE DISRUPTION

Many of the body's functions are regulated by the glands and hormones that make up
the endocrine system. It takes only tiny amounts of these hormones—hormones like
estrogen, testosterone, thyroid hormone, insulin, and many others—to control
the development and actions of the rest of the body.

A number of manufactured chemicals can mimic one or more hormones; that is, the chemical
may look enough like a specific hormone that it can trigger the response of the endocrine
system. For example, the well-known chemical bisphenol A (or BPA) can bind to estrogen
receptors, tricking the body into thinking that there is more—or less—estrogen
than is actually present. Because hormones are used in very small amounts to send
signals through the body, very low levels of these endocrine-disrupting chemicals (EDCs)
can have large effects. This is especially true when hormonal systems, like the
thyroid or the reproductive system, is developing during pregnancy and through
puberty.

Some PFAS chemicals, notable PFOA, show evidence of endocrine-disrupting effects in
lab animals and in humans. PFOA has been shown to modulate the effects of a
specific hormone-sensing molecule, called PPARα, but is likely to have effects on
other hormone systems as well.
→ REFERENCE
Endocrine disrupting properties of perfluorooctanoic acid
One epidemiologic study found
a nearly three-fold risk of overweight/obesity in daughters of women
highly exposed to PFOA; this is likely related to the hormone-mimicking
effects of PFOA on PPARα, although it may also be related to PFOA's
thyroid effects.
→ REFERENCE
Halldorsson et al. 2012. Prenatal Exposure to Perfluorooctanoate and Risk of Overweight at 20 Years of Age: A Prospective Cohort Study
A laboratory study in rats indicates that PFOS can affect the way the brain
uses hormones to help regulate other organ systems.
→ REFERENCE
US EPA, Emerging Contaminants - Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA), March 2014

If you found these examples confusing or uncertain, you are not alone. Endocrine
disruption is a subtle and difficult subject to study. For the moment, it is clear
that PFAS chemicals appear to interfere with at least several different hormone
systems. Research in this field will be ongoing for some time to come.

POPULATIONS ESPECIALLY AT RISK

For many toxicants, we can identify populations who are at especially high risk.
For example, as we have noted above, children (and fetuses in utero) are
more susceptible to developmental effects, especially through endocrine disruption.
The thyroid, for example, helps control growth and metabolism, and these
processes could be altered by PFOA's effects on thyroid hormone.

Unfortunately, kids also tend to have higher levels of PFAS exposure than
adults do. This might be due to higher exposures (for example, if a kid's
diet has more PFAS in packaging materials), or it might be biological (for
example, if kids don't metabolize and excrete PFAS as well as adults).

While some people might be more biologically susceptible to toxins like PFAS,
there can also be social or behavioral reasons that a particular group might be
subjected to unusually high levels of exposure. For example, studies have shown
that communities of color are more likely to be burdened by toxic emissions;
moreover, the siting of the polluting facilities is partly determined by the
presence of those communities of color.
→ REFERENCE
Morello-Frosch et al. (2002), Environmental justice and regional inequality in southern California: implications for future research
This type of problem, which has been termed environmental racism, plays an
important role in the unequal exposure to toxics in the United States.
(The relationship of PFAS contamination to race, income, and other social factors
has not yet been studied.)

PFAS is a large class of chemicals that includes many related compounds.
Only PFOA and PFAS
have been even moderately well studied thus far.

We are really just getting started learning about the effects of PFAS.
In fact, we know there are specific PFAS chemicals already in widespread
use that scientists haven't even
identified, never mind studied.
This is a serious problem with our chemical regulatory system: See #future.

Now that we know about the contamination, are we still being exposed?
Although PFAS have been in use for decades—and although public health
scientists have expressed concerns about them for many years—they have
been essentially unregulated until recently.

The US regulatory system does not generally require any testing before new chemicals can be used.
Furthermore, in most cases, chemicals cannot be regulated
until they are proven to be toxic.

The presence of several large contamination incidents has now created
enough public awareness that manufacturers have now voluntarily stopped making the most
heavily-used PFAS chemicals. (These chemicals may still be used abroad, however,
and these products are still imported to US.)
Unfortunately, in most cases, we don't yet know what chemicals are being used to replace them,
althought it is very likely that most of the replacements
are also PFAS chemicals.

This demonstrates a serious imbalance between government and industry:
Manufacturers can change their products at will, but EPA is required to
accumulate many years of scientific evidence before regulating a new
chemical.

As one scientist recently pointed out,
we know that there are PFAS being used out there that we haven't even yet
identified!

In November 2016, EPA issued a health advisory for PFOA and PFOS, setting
guidance for permissible limits of these chemicals in drinking water.
→ REFERENCE
US EPA, Drinking Water Health Advisories for PFOA and PFOS

See #safe for details.
For more about regulating chemicals like PFAS, see #future

See also, Should I #filter my water?
Testing water for PFAS contamination is possible, although
because PFAS chemicals are so widespread, even collecting a
sample to be tested can be a difficult process.
While costs vary widely, a test for PFAS in water will cost several hundred dollars.

US EPA Method 537
→ REFERENCE
US EPA, Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
specifies the collection and testing process in great
detail, and this process should be followed if results will be used in any
official or legal process. While Method 537 provides information on
testing for a number of PFAS, it does not test for all of them. Some
test facilities may report only PFOA, or PFOA and PFOS, or another limited
set of PFAS.

The good news is that, if you are on a public water system, your system
managers are responsible for this testing. They may already have test
results, or may be able to get them.

If you receive water from a public supply, your water utility is required to
provide you with an annual Consumer Confidence Report describing what tests have
been performed, and explaining any cases in which the water failed federal water
quality requirements. You can find your Consumer Confidence Report
through the EPA's search
tool, or just try searching for your town's name and the phrase "water quality report"
or similar keywords.
Check your water system's CCR to find out what levels were measured in your local
system, and when and where.

If you're on a well, ask your regular water testing service about
testing for PFAS. Be sure to follow up with your local and state
departments of health and environment to make sure they are aware of your
concerns. In some cases, they may be able to connect you with other
resources. If your groundwater is contaminated, it is likely that the
whole aquifer—the underground body of water your well draws from—is
also contaminated; so it is important that others know about your results.

For details on how to interpret test results, see #interpretFor the question of what level of PFAS contamation is "safe", see #safeFor information about treating water and reducing your PFAS exposure, see #reduce

Testing for PFAS in blood is difficult and expensive, and can only be done
by a small number of laboratories.

Before testing for PFAS in blood, it may be more useful to identify the sources
of the PFAS—for example, by determining whether your drinking water is
contaminated. If that's the case, you'll have better information about how you
were exposed, and how you can reduce your exposure.

Unfortunately, if you have elevated levels of PFAS in your blood, there is
nothing that can be done to remove the PFAS. The best thing you can do is to
identify the source of your exposure, and prevent further exposure.

If you are concerned about PFAS exposure through contaminated
water in your community,
make sure you've tested your water supply first, and investigated possible
sources of contamination.
If you can show that you are exposed to PFAS in your water, that may be all you need to
know. If you're exposed above the "safe" level, your local government
should be taking steps to reduce the contamination. Even if your water is
contaminated below a "safe" level, you should still be able to pressure
your local government and water supplier to reduce the contamination.
Proving that the PFAS is also in your blood may not be necessary.

For information on testing of PFAS in water, see #waterFor information on what level of PFAS contamination is "safe", see #safe

If your community has been exposed to high levels of PFAS, your local
department of health may be able to put together a blood testing program.
Contact your local or state health agency and ask about having your
community tested.

If your department of health is not offering blood tests for PFAS, and if
you have reason to be especially concerned about your PFAS exposure,
talk to your healthcare provider about a blood test. However, this test
may be quite expensive, and will probably not be covered by your medical
insurance.

One final caution: Test methods for the most common PFAS chemicals, especially PFOA
and PFOA, are well established. However, tests for other PFAS chemicals may be less
common or more difficult. If you are concerned about a specific PFAS chemical, make
sure that one will be analyzed. It isn't possible to test a sample for all
chemicals; chemists typically need to know which specific ones they are looking for.

For information about interpreting your blood test results, see #interpret

Several large-scale testing programs have been done in response to
specific contamination incidents. To get a sense of what is required,
see Vermont's PFOA blood testing program
→ REFERENCE
Vermont's PFOA blood testing program
and the C8 Science Panel's medical monitoring program.
→ REFERENCE
C8 Science Panel screening program

My test showed that I have PFAS in my blood. How should I interpret this result?

The extremely widespread use of PFAS means that almost all Americans now
have PFAS in their bodies and in their blood. As
test methods become more sensitive, we are able to find PFAS at lower and
lower levels. Currently, about 99% of Americans tested have detectable
levels of PFAS in their blood. Remember, a detectable level of PFAS does
not indicate a specific health concern or health risk.

The US federal government's National Health and Nutrition Examination Survey
(NHANES) provides a great deal of data on PFAS levels in blood, so anyone can
compare their specific results with results from others. This will give you a
sense for whether your specific PFAS exposure is high, or medium, or at the
"background" level of average everyday exposure. We will discuss this data
at #compare
below.

Comparing to other people is useful in giving your context about whether your
exposure is high or low, in comparison with other who have been tested. But we
don't know enough about PFAS to connect any amount in blood with specific health
problems, so the blood test itself won't tell you about any specific health
concerns that may relate to PFAS exposure now or in the future. Some people
might have relatively high amounts of PFAS in their blood, but not have health
effects from PFAS, while others might be more susceptible. For example,
developing children and fetuses are more susceptible to the endocrine disrupting
effects on the thyroid, the brain, or the immune system, since those hormonal
systems are still being formed and are especially sensitive. Unfortunately, kids
also tend to have higher levels of PFAS exposure than adults do. This might be
due to higher exposures (for example, if a kid's diet has more PFAS in packaging
materials), or it might be biological (for example, if kids don't metabolize and
excrete PFAS as well as adults).

The best thing you can do is to reduce any continued exposure to yourself, your
family, and your community. Also, let's try to fix our broken chemical
regulatory system so that this problem doesn't happen again. See #future.

Much more detail about the terminology used in interpreting your results is
available in the longer answer to this question.

INTERPRETING YOUR RESULTS

When interpreting your blood test results,
look at your own value and compare it to the range
and the median in your community and in other communities studied.
If you are given a percentile for your results, that may be the most
useful measure to see where you stand among your community members.

The glossary of terms below may help with understanding your results and
comparing your results to others'.
We'll also show you some data on exposure levels in different groups, to help you
compare your PFAS concentrations to other people.

PFAS CONCENTRATIONS IN WATER

PFAS concentrations in water are typically measured in one of the following units:
ppb: parts-per-million: 1 ppm is equal to one gram of PFAS in one million grams of water.
ppb: parts-per-billion: 1 ppb is equal to one gram of PFAS in one billion grams of water.
ppt: parts-per-trillion: 1 ppt is equal to one gram of PFAS in one trillion grams of water.

When intepreting your drinking water results, keep in mind that there is no
simple connection between your water PFAS levels and your blood PFAS levels.
High levels of PFAS in water are likely to contribute to your body burden,
but other sources, and individual factors,
can also influence your body burden of PFAS.

PFAS CONCENTRATIONS IN BLOOD

PFAS in blood are most commonly measured in units of
μg/L—micrograms of PFAS per liter of blood; or
ng/mL—nanograms of PFAS per milliliter of blood

Conveniently, μg/L and ng/mL work out to be the same units! So if your
test result tells you that you have 58 μg/L, you may also read that as 58
ng/mL—the two units mean the same thing.
Don't get concentrations in drinking water confused with concentrations in blood!
Fortunately, they are usually referred to by the different units described
above.

See below for information on comparing your water and blood results with others'.
For the question of how much is too much, see #safe.

STATISTICAL TERMS

Your lab reports may use some of the following terms.
If you have trouble interpreting your results, or you have other
questions, contact Toxics Action Center.

PERCENTILES are often used to indicate how your result compares to other
people's. Your percentile tells you how much of the population has blood
concentrations lower than yours. (You may be familiar with percentiles
from standardized testing and other uses.)

For example, if you are in the 94% percentile, your blood concentration is higher
than 94% of the population: In this case, you would seem to be fairly highly
exposed. If you are in the 25% percentile, however, most of the population --
about 75%—has higher blood concentrations than you do.

The MEDIAN concentration is the 50% percentile. That is, half of the population
has concentrations above the median, and half has concentrations below the
median. If you are at the median concentration, you have very "average"
concentrations. Remember, this doesn't tell you whether you are or are not at
risk!

The MEAN is the "average" in the usual sense of the term. For our purposes, the
MEAN is much less useful than the MEDIAN, because one very high or very low result
can change the mean dramatically (but will not affect the median).

The GEOMETRIC MEAN (or GEOMEAN) is another way of calculating the mean for some
types of data. This is more useful than the MEAN for our purposes; however, the
GEOMETRIC MEAN can still be affected by a single very high or low data point.

The RANGE simply tells us the highest and lowest values in the data. If the RANGE is 12
to 98 ng/g, the most exposed person has 98 ng/g in their blood.

The LEVEL OF DETECTION (or LOD) corresponds to the lowest concentration of PFAS that
the laboratory can measure. For example, if the LOD is 0.1 ng/g, this means that
the lab cannot detect PFAS below 0.1 ng/g. If your blood concentration is lower
than the LOD, the report will most often say "<LOD" or "<0.1 ng/g" to indicate
that your specific level is undetectably low. (The lab won't usually report a
"0", because you might have a very small amount that is too small to be detected.)
Different laboratories and different methods will have different levels of
detection.

In 2011-2012, the geometric mean of blood PFOA concentrations—a good measure
of the average exposure for this type of data—was 2.08 μg/L. The 95%
percentile was 5.68 μg/L; that is, 95% of the population had less than 5.68
μg/L of PFOA in their blood.
→ REFERENCE
Fourth National Report on Human Exposure to Environmental Chemicals (updated January 2017).
A sketch of this distribution is shown below.
By comparison, a sample of residents of Hoosick Falls, NY, where the drinking water
was contaminated with PFOA, found a geometric mean of 23.5 μg/L. Notice that
this "average" value in Hoosick Falls residents is far higher than even the 95th
percentile of the NHANES (background) data; in fact, it is too high to fit on our
chart above.

How concerned should we be about PFAS in our water or our blood?
When we talk about "safe levels" of exposure, it is critical to distinguish
between blood levels and
drinking water levels. Someone with a "safe" level
of PFAS in their water might still have high levels of PFAS in their blood. In
fact, the scientific data indicates that most Americans get the majority of their
PFAS exposure from sources other than drinking water.

Unfortunately, we simply don't know enough about the toxicity of PFAS to
determine whether a certain amount of PFAS in blood is "safe". The best you
can do with blood results is to compare them with others' to see if yours are
elevated—see #interpret
for more information.

If you receive water from a public supply, your water utility is required to
provide you with an annual Consumer Confidence Report describing what tests have
been performed, and explaining any cases in which the water failed federal water
quality requirements. You can most often find your Consumer Confidence Report
online—try searching for your town's name and the phrase "water quality report"
or similar keywords.

In November 2016, EPA issued a health advisory for PFOA and PFOS.
For more information about this health advisory, see the longer answer to
this question.
EPA's health advisory sets a maximum of 70 ppt (parts-per-trillion) for the
combined concentration of PFOA and PFOS in drinking water.
→ REFERENCE
US EPA, Drinking Water Health Advisories for PFOA and PFOS

However, some experts have critized EPA's standard as permitting too much PFAS in
drinking water. The environmental advocacy organization Environmental
Working Group has argued that the standard should be ten times lower—ten
times more protective—at about 7 ppt.
→ REFERENCE
Environmental Working Group, Teflon Chemical Harmful at Smallest Doses

Other governments have set different thresholds for the maximum
amount of PFAS allowed in water.
For example, the Vermont Department of Health has set its
drinking water health advisory level at 20 parts per trillion (20 ppt),
far lower—and therefore more protective—than the US EPA's standard.
→ REFERENCE
Vermont Department of Environmental Conservation, Interim PFOA and PFOS Standards

Check your water system's CCR to find out what levels were measured in your local
system, and when and where. See #water
for more information.

Note: EPA's health advisory refers to PFOA and PFOS because these two chemicals have been most heavily studied—but EPA has not set limits for other PFAS chemicals, although many are likely to have similar effects.

These numbers—whether EPA's advisory value of 70 ppt, or the lower levels
of 7 ppt suggested by EWG—seem very small!
But remember, PFAS—like many other industrial chemicals --
accumulate in the body, and are only slowly excreted.
Your body and blood concentrations of PFAS are likely to be significantly higher
than the concentration in the water you drink!

Some critics suggest that concentrations of chemicals in the parts-per-billion
(ppb) or parts-per-trillion (ppt) range are too small to have an effect on the
body. But health effects are all about
having the right molecules in the right places—and even a small number
of molecules can be important. To take one example, Viagra causes
its famous effects at a blood concentration of about 3 ppb
Similarly, very small concentrations of toxins can have important effects,
especially on susceptible populations.

Can I reduce the amount of PFAS already in my body?
How can I reduce future exposures?
Is it safe to shower/bathe in PFAS-contaminated water?
What about food and food packaging?

For specific details on water filtration, see #filter below.
After decades of production and use, about 99% of Americans tested now
have detectable levels of PFAS in their blood. Remember, a detectable
level of PFAS does not indicate a specific health concern or health risk.

REDUCING YOUR PFAS LEVELS

The body will naturally metabolize and excrete PFAS over time. However,
this is a very slow process: It is estimated to take 2-4 years to eliminate
half of the PFOA from the body.
There is no proven way to speed up this elimination of PFAS chemicals from the body.
"Toxic eliminating" diets or supplements are not likely to have any effect
on PFAS levels.

The persistence of PFAS is one reason
why preventing future exposure is so important.
For details about how to lower your exposure to PFAS in drinking water,
see the longer answer to this question.

Note: A handful of the most hazardous toxicants can sometimes be removed medically; for example, chelation therapy can remove lead from blood. However, these methods are very difficult and extremely invasive, and are only last-ditch approaches to be used in the most extreme cases under careful medical supervision. There is no such approach to lowering PFAS already in the blood.

Overall, preventing future PFAS exposure to yourself, your family, and
your community is the best way to avert further health impacts.

Of course, paying attention to proper diet and exercise are the very
best things you can do to improve your overall health and to reduce
health risks.

PREVENTING FUTURE PFAS EXPOSURE

The best thing that you can do right now
is to reduce further exposure to PFAS.
First, find out about PFOA in your drinking water sources.
If you are on a public water supply, your water utility is responsible for
making sure your water meets federal and state criteria.
See #water
for details about having your water system tested.
If you are on a private well, you may have to have the water tested
yourself. See #water
for details.
Be sure to follow up with your local and state departments of health
and environment to make sure they are aware of your concerns. In some
cases, they may be able to connect you with other resources.

TREATING DRINKING WATER

Contaminated water can be treated at home by water filters only if they
are specifically designed to remove PFAS. Most commercial water filters
are not.

For more information, see #filter.

Is it safe to shower/bathe in PFAS-contaminated water?

(TK)

FOOD AND OTHER EXPOSURE ROUTES

Other sources of PFAS can be significant for some people.
PFOA, other PFAS, and related chemicals
can be found in many food packaging materials,
including microwave popcorn bags and pizza boxes.
(These chemicals are useful because they prevent oils and greases from
binding to the packaging material.)

If you rely on a lot of packaged food,
you might want to ask your local groceries or the food manufacturers
whether they use PFAS (and other toxic chemicals). Although they may not
be able to tell you, and they may not even know, this is one small way to
raise awareness of the problem.

Finally, if your local rivers or streams are known to be polluted with
PFAS, fish caught in those water bodies might also be polluted. If this
is the case, consider practicing catch-and-release fishing instead of
eating your catch. Call your local and state departments of the
environment, or your fish and game agency, and ask about having fish
tested for PFAS.

Do commercial filters (e.g. Brita) work for PFAS and other emerging contaminants?
Does boiling water help eliminate PFAS?
Is distilled water safe from PFAS?
Is bottled water safe from PFOA?
Contaminated water can be treated at home by water filters only if they
are specifically designed to remove PFAS. Most commercial water filters
are not.

(DO WE HAVE RECOMMENDATIONS FOR FILTERS?)

Many people see bottled water as a solution—and in cases
where the water system is known to be contaminated, it may be necessary.
However, bottled water is very poorly regulated. In addition, the
environmental footprint of transporting bottled water, and of bottle
waste—almost always plastic—is very high. In cases where PFAS
contamination can be treated at the source, drinking clear tap
water, perhaps
treated with a simple activated carbon filter, is usually the most
environmentally sound and healthiest approach.

Boiling water is useful to kill living parasites—
including bacteria and viruses—in contaminated drinking water. However,
this approach isn't effective with most toxics. PFAS is quite stable and
persistent, and boiling water is unlikely to remove any significant amount of
it.

While filtration may be useful, the best approach for significantly
contaminated water will be to make sure your water supplier manages
contamination of the aquifer at the source. See #reduce
and #water for more information.

If you know or suspect that your community's water has been contaminated with
PFAS, a good starting place is to get your #water
tested.
Be sure to check the #CCR
published by your water supplier for information on what testing they've already
done.
If your water supply is not testing for PFAS, pressure your local government to have
the water tested.
If your water is contaminated, be sure your state and local health officials know
about the problem. If the contamination is below the EPA's #advisory,
they may not be willing (or required) to act. However, check guidance from other
states and localities to see if you exceed guidelines set elsewhere.

It's important to identify the source of
contamination. Are there major
sources—for example, heavy use of fire-fighting foams—in your area?
If the source is not already known, your state and local health officials may be
able to help you track it down.
If your water is contaminated,
you may want to have your #blood
tested as well. Remember, testing—especially blood testing—is expensive.
Talk to your state and local officials about setting up a monitoring program.

Get organized!

You can't respond to contamination alone—you'll need the help of your neighbors
and friends, as well as scientists and government officials.
You need to organize!
A number of resources exist to help your community get organized to fight
pollution. If you know of groups in your area, contact them and ask for help.
You can always contact
Toxics Action Center for
connections and next steps.

In addition to organizing help, you may need expert assistance to help your
community understand their contamination, the possible effects, and the best ways to
respond. Consider contacting local colleges and universities (especially
schools of public health) for assistance.
Toxics Action Center, and other
that focus on community health and environmental justice, should also be able to
connect you with scientists who can help.

Is a health study right for your community?

Many communities immediately decide that they need the state to perform a health
study of their community to evaluate the effect of the pollution. While a health
study can provide important information, it might also prove inconclusive, and in
either case it is likely to take a substantial investment of time and resources.

If you've done the basic background work above, and you think that a health study is
the right next step, see our guide, Is a Health Study Right
for Your Community?. This guide will help you establish your research
question and develop the best study to answer your community's questions.

How can we make sure contamination like this doesn't happen in the future?

What can we do to promote responsible chemical use & development?
How can chemists find safer chemicals?
Are the C6 chemicals good replacements for the C8 PFAS chemicals
The current situation—in which millions of Americans are exposed to
PFOA, PFOS, and probably to other PFAS in their drinking water—should never have happened.
→ REFERENCE
'Unsafe levels of toxic chemicals found in drinking water for six million Americans'

It happened because we allowed a chemical to be used widely and at high
volumes before we had adequately tested it.
This is not an isolated incident or a one-time occurance.
The same thing happened with leaded gasoline, and with lead in paint. The
same thing happened with flame retardants and with bisphenol A. Incidents
like these, and many more, happen because of the design of the US
regulatory system, which over the past 40 years has not required companies
to test chemicals before using them.
(This situation may now be changing; see below for information on changes
to federal
regulations.)

By contrast, European chemicals regulation requires extensive testing for
human and environmental health effects before a chemical can be placed on
the market—summed up in the simple phrase, "no data, no market".

The difference between these two systems lies in who has the burden of
proof. In Europe, a chemical manufacturer must prove a chemical safe
before it is used. In the US, the government must prove that a chemical
is harmful before its use can be stopped.
The response to concerns about PFOA contamination has followed the
usual path.
As chemicals come under scrutiny, and start being studied for their
health effects, manufacturers typically stop dumping the chemicals,
preferring to dispose of them more responsibly or to recycle them.
For example, Dupont's contamination of the air and water around its
Parkersburg, WV facility had been going on for decades before 1999, when a
a WV farmer sued the company alleging that the company's PFOA emissions
had sickened his cows.
→ REFERENCETHE TEFLON TOXIN: DuPont and the Chemistry of Deception
Within a few years, under intense public scrutiny, Dupont dramatically
reduced its emissions.
As we have learned more about the effects of PFOA and PFOS, they have been
used less and less. By 2013, DuPont it had eliminated the use of PFOA
altogether—without the chemical having been regulated.
In some cases, EPA will negotiate an end to production with a company
rather than attempting to pass a contentious new regulation.

Today, we know much more about the effects of PFOA and PFOS, and
EPA has now set standards for drinking water (see #safe).
This appears to be a successful end to the PFOA/PFOS story—and it
certainly is an improvement—but this approach really
underscores the EPA's lack of authority to regulate chemicals of concern.
Halting production of PFOA doesn't end consumer exposure,
since PFOA and PFOA-containing products can still be imported,
and since these chemicals will remain in the environment long
after they have been released.

ALTERNATIVE CHEMICALS AND "REGRETTABLE SUBSTITUTION"

It's important to note that the PFOA/PFOS health advisories address only past
contamination by these two known PFAS chemicals.
As they phased out PFOS/PFOA, manufacturers started using
alternative or substitute chemicals in their place.
But these substitutes may be entirely new and completely unstudied molecules.
Even their specific identity is often
protected as confidential business information; therefore, it can't be
studied by researchers outside the industry.
Scientists sometimes call this process "regrettable substitution", as it's quite
possible that the new chemical might be as bad as the one we phased out.

Indeed, finding alternatives to dangerous chemicals is a serious
challenge. Let's take the example of BPA ("bisphenol A"), a name you
probably recognize know from seeing "BPA-free" labels on water bottles.
"BPA-free" sounds great, right? But what the label doesn't tell you is
what chemical is used instead of BPA, and whether that chemical is any
safer. In some cases, the alternative to BPA is BPS or "bisphenol S"—a
chemical which has only recently been studied, but which appears to have
similar toxic effects as its close cousin BPA. Have we made any progress?

In the case of PFAS chemicals like PFOA and PFOS,
some scientists are now concerned that companies are switching to the "C6" chemicals.
These perfluorinated chemicals have six carbons, instead of the eight carbons in
PFOA or PFOS, but otherwise are very similar to their bigger cousins. In
fact, the C6 chemicals are likely to be more soluble in water, to move
more easily through the environment, and to be taken more readily into the
human body.

Scientists know very little about the C6 chemicals; but it is quite likely that
some companies are already using them today. Someday soon, you may see a label on
your water-repellent jacket that says "no PFOA or PFOS"—but you won't know
whether they are using C8, or a new C6 chemical, or some completely
different (and possibly unstudied!) chemical.

AN UNFOLDING STORY

We have limited information about PFOA and PFOS
— but we have much less information about other PFAS!
In fact, experts consider it almost certain that there are specific PFAS
chemicals in use that we haven't even identified, never mind studied.
And even when we've addressed the existing set of PFAS chemicals,
there are certain to be new ones—for example, the short-chain "C6"
chemicals—that will enter commerce over the next few years.
If we don't learn from our mistakes now, we could face the same problem with
those in the future.